A slot is a narrow opening, especially one designed to receive something, such as a coin or piece of mail.

To play a slot machine, the player inserts cash or, in “ticket-in, ticket-out” machines, a paper ticket with a barcode into a designated slot on the machine. The machine then activates a series of reels that spin and stop to rearrange symbols. When the machine displays a winning combination, the player earns credits based on the paytable. The symbols and bonus features vary by machine, but classics include fruits, bells, stylized lucky sevens, and other symbols aligned with a theme.

Each advance in the technology of slot machines inspired commensurate innovation among cheaters. From plugged nickels to Jenny’s Shaker, the tools grew ever more sophisticated—but security was always one step ahead. By the time Carmichael was busted at Denny’s, slots had come a long way from their nickel-plated, side-handled origins.

Slot manufacturers now face a dilemma. While slots still appeal to players who want to zone out in front of a machine that’s not physically or mentally taxing, younger gamers raised on video games are demanding more skill-based gameplay. The industry has responded by embracing data collection to learn more about the traits that make a slot game successful. Firms like ReelMetrics help slot developers cull the most effective elements from existing games, and use them to design superior new games that attract and retain players. Other companies—including Scientific Games, which just launched SG Connect—provide their operator customers with valuable player behavioral insights in order to increase casino profitability.